Used unjittered projection matrix for a sharper and more stable TAA

libraries/gpu/src/gpu/Context.cpp

@@ -174,6 +174,11 @@ void Context::getStereoViews(mat4* eyeViews) const {
     }
 }
 
+void Context::setProjectionJitter(float jx, float jy) {
+	_projectionJitter.x = jx;
+	_projectionJitter.y = jy;
+}
+
 void Context::downloadFramebuffer(const FramebufferPointer& srcFramebuffer, const Vec4i& region, QImage& destImage) {
     _backend->downloadFramebuffer(srcFramebuffer, region, destImage);
 }

libraries/gpu/src/gpu/Context.h

@@ -208,6 +208,8 @@ public:
     void setStereoViews(const mat4 eyeViews[2]);
     void getStereoProjections(mat4* eyeProjections) const;
     void getStereoViews(mat4* eyeViews) const;
+	void setProjectionJitter(float jx, float jy);
+	gpu::Vec2 getProjectionJitter() const { return _projectionJitter; }
 
     // Downloading the Framebuffer is a synchronous action that is not efficient.
     // It s here for convenience to easily capture a snapshot
@@ -254,6 +256,7 @@ protected:
     FramePointer _currentFrame;
     RangeTimerPointer _frameRangeTimer;
     StereoState  _stereo;
+	gpu::Vec2 _projectionJitter{ 0.0f, 0.0f };
 
     // Sampled at the end of every frame, the stats of all the counters
     mutable ContextStats _frameStats;

libraries/render-utils/src/AntialiasingEffect.cpp

@@ -541,6 +541,7 @@ void JitterSample::run(const render::RenderContextPointer& renderContext) {
 
         args->_context->setStereoProjections(projMats);
     }
+	args->_context->setProjectionJitter(jx, jy);
 }
 
 

libraries/render-utils/src/DeferredFrameTransform.cpp

@@ -38,9 +38,6 @@ void DeferredFrameTransform::update(RenderArgs* args) {
 
     args->getViewFrustum().evalProjectionMatrix(frameTransformBuffer.projectionMono);
 
-	frameTransformBuffer.previousProjection[0] = frameTransformBuffer.projection[0];
-	frameTransformBuffer.previousProjection[1] = frameTransformBuffer.projection[1];
-
     // Running in stereo ?
     bool isStereo = args->isStereo();
     if (!isStereo) {
@@ -48,6 +45,11 @@ void DeferredFrameTransform::update(RenderArgs* args) {
         frameTransformBuffer.stereoInfo = glm::vec4(0.0f, (float)args->_viewport.z, 0.0f, 0.0f);
         frameTransformBuffer.invpixelInfo = glm::vec4(1.0f / args->_viewport.z, 1.0f / args->_viewport.w, 0.0f, 0.0f);
         frameTransformBuffer.invProjection[0] = glm::inverse(frameTransformBuffer.projection[0]);
+
+		frameTransformBuffer.projectionUnjittered[0] = frameTransformBuffer.projection[0];
+		frameTransformBuffer.projectionUnjittered[0][2][0] -= args->_context->getProjectionJitter().x;
+		frameTransformBuffer.projectionUnjittered[0][2][1] -= args->_context->getProjectionJitter().y;
+		frameTransformBuffer.invProjectionUnjittered[0] = glm::inverse(frameTransformBuffer.projectionUnjittered[0]);
 	} else {
 
         mat4 projMats[2];
@@ -60,6 +62,11 @@ void DeferredFrameTransform::update(RenderArgs* args) {
             auto sideViewMat = projMats[i] * eyeViews[i];
             frameTransformBuffer.projection[i] = sideViewMat;
             frameTransformBuffer.invProjection[i] = glm::inverse(sideViewMat);
+
+			frameTransformBuffer.projectionUnjittered[i] = frameTransformBuffer.projection[i];
+			frameTransformBuffer.projectionUnjittered[i][2][0] -= args->_context->getProjectionJitter().x;
+			frameTransformBuffer.projectionUnjittered[i][2][1] -= args->_context->getProjectionJitter().y;
+			frameTransformBuffer.invProjectionUnjittered[i] = glm::inverse(frameTransformBuffer.projectionUnjittered[i]);
 		}
 
         frameTransformBuffer.stereoInfo = glm::vec4(1.0f, (float)(args->_viewport.z >> 1), 0.0f, 1.0f);

libraries/render-utils/src/DeferredFrameTransform.h

@@ -47,15 +47,16 @@ protected:
 		glm::mat4 projection[2];
 		// Inverse proj matrix or Left and Right proj matrix going from Mono Eye space to side clip space
 		glm::mat4 invProjection[2];
-		// Mono proj matrix or Left and Right proj matrix going from Mono Eye space to side clip space of
-		// the previous frame
-		glm::mat4 previousProjection[2];
 		// THe mono projection for sure
         glm::mat4 projectionMono;
         // Inv View matrix from eye space (mono) to world space
         glm::mat4 invView;
         // View matrix from world space to eye space (mono)
         glm::mat4 view;
+		// Mono proj matrix or Left and Right proj matrix going from Mono Eye space to side clip space without jittering
+		glm::mat4 projectionUnjittered[2];
+		// Inverse proj matrix or Left and Right proj matrix going from Mono Eye space to side clip space without jittering
+		glm::mat4 invProjectionUnjittered[2];
 
         FrameTransform() {}
     };

libraries/render-utils/src/DeferredTransform.slh

@@ -32,10 +32,11 @@ struct DeferredFrameTransform {
     vec4 _stereoInfo;
     mat4 _projection[2];
     mat4 _invProjection[2];
-    mat4 _previousProjection[2];
     mat4 _projectionMono;
     mat4 _viewInverse;
     mat4 _view;
+	mat4 _projectionUnJittered[2];
+	mat4 _invProjectionUnJittered[2];
 };
 
 uniform deferredFrameTransformBuffer {
@@ -63,6 +64,12 @@ mat4 getProjection(int side) {
 mat4 getProjectionMono() {
     return frameTransform._projectionMono;
 }
+mat4 getUnjitteredProjection(int side) {
+	return frameTransform._projectionUnJittered[side];
+}
+mat4 getUnjitteredInvProjection(int side) {
+	return frameTransform._invProjectionUnJittered[side];
+}
 
 // positive near distance of the projection
 float getProjectionNear() {
@@ -139,6 +146,14 @@ vec3 evalEyePositionFromZdb(int side, float Zdb, vec2 texcoord) {
     return eyePos.xyz / eyePos.w;
 }
 
+vec3 evalUnjitteredEyePositionFromZdb(int side, float Zdb, vec2 texcoord) {
+    // compute the view space position using the depth
+    vec3 clipPos;
+    clipPos.xyz = vec3(texcoord.xy, Zdb) * 2.0 - 1.0;
+    vec4 eyePos = frameTransform._invProjectionUnJittered[side] * vec4(clipPos.xyz, 1.0);
+    return eyePos.xyz / eyePos.w;
+}
+
 vec3 evalEyePositionFromZeye(int side, float Zeye, vec2 texcoord) {
 	float Zdb = evalZdbFromZeye(Zeye);
     return evalEyePositionFromZdb(side, Zdb, texcoord);

libraries/render-utils/src/velocityBuffer_cameraMotion.slf

@@ -28,11 +28,11 @@ void main(void) {
 	float Zdb = texelFetch(depthMap, ivec2(gl_FragCoord.xy), 0).x;
 
 	// The position of the pixel fragment in Eye space then in world space
-    vec3 eyePos = evalEyePositionFromZdb(stereoSide.x, Zdb, texcoordPos);
+    vec3 eyePos = evalUnjitteredEyePositionFromZdb(stereoSide.x, Zdb, texcoordPos);
 	vec3 worldPos = (getViewInverse() * vec4(eyePos, 1.0)).xyz;
     
     vec3 prevEyePos = (getPreviousView() * vec4(worldPos, 1.0)).xyz;
-    vec4 prevClipPos = (frameTransform._projection[stereoSide.x] * vec4(prevEyePos, 1.0));
+    vec4 prevClipPos = (getUnjitteredProjection(stereoSide.x) * vec4(prevEyePos, 1.0));
     vec2 prevUV =  0.5 * (prevClipPos.xy / prevClipPos.w) + vec2(0.5);
 
     //vec2 imageSize = getWidthHeight(0);